Well drilling bit



y A. w. KAMMERER 2,320,136

WELL DRILLING BIT Filed Sept. 30, 1940 fig. 1. f)! 2. x

r' if ARcHER WKZMMERE Patented May 25, 1943 UNITED STATES PATENT OFFICE WELL panama BIT Archer W. Kammerer, Fullerton, Calif.

Application September 30, 1940, Serial No. 358,946

2 Claims.

This invention relates to earth boring tools, and more particularly to drilling bits used in the rotary drilling of oil, water, gas, sulphur and similar wells.

The present case is a continuation-in-part of my prior application entitled Well drilling bits, Serial No. 310,567, filed December 22, 1939.

In the application above referred to, there is disclosed a composite rotary drilling bit having side roller gauge or reaming cutters for removing the outer portions of formation material from the hole bottom and also intermediate drag cutters for removing the central portion of material from the bottom inside of the annular path traced by the side cutters. One of the features of invention in that case is the elevation of the bottom cutting edges of the drag cutters above the lowermost positions occupied by the teeth on the roller cutters, which not only inherently produces vertical drilling by the bit, but also causes very effective action of the drag cutters upon 7 both hard and soft formations.

While the elevation of the bottom cutting edges on the drag cutters is desirable, the extent to which they can be raised has heretofore been limited, since the inner tooth faces of the side roller cutters tend to rub against the inclined inner annular shoulder formed by their radial teeth in the bottom of the bore hole being produced. These inner tooth faces have very little effect in removing the shouldered formation pertion, merely riding on it as the bit rotates and preventing adequate penetration of the drag cutters into the formation Accordingly, it is an object of the present invention to provide a rotary drill bit which permits its central cutters to be elevated above the side cutters to a greater extent than heretofore, improving the inherent tendency of the bit to drill a vertical hole. In the specific example shown in the drawing, this is accomplished by including reaming teeth on the inner faces of the side cutters, so that the inner annular shoulder on the bottom of the hole is removed by a ream ing action and does not retard progress of the bit. Instead, the rate of penetration in the formation is increased.

A further object of the invention is to provide an improved sturdy bearing construction for the roller cutters of a drill bit.

Yet another object of the invention is to provide an improved bearing construction for the side rollers of a drill bit, the bearing construction being held firmly in assembled relationship by attachment to the cross cutters of the bit.

This invention possesses many other advantages and has other objects which will become apparent from a consideration of I the embodiment shown in the drawing accompanying and forming part of the present specification. This form will now be described in detail to illustrate the general principles of the invention, but it is to be understood that such detailed description is not to be taken in a limited sense, since the invention is best defined in the claims appended hereto. 1

Referring to the drawing:

Figure 1 is an elevational view of a drill bit, parts being removed for the purposes of clarity, and other portions being shown in section;

Figure 2 is a longitudinal section taken generally along the line 2-2 of Figure 1; and

Figure 3 is an enlarged longitudinal section through one of the side roller cutters and its bearing support.

As seen in the drawing, the drill bit includes a main body or shank 10 having the usual threaded, tapered pin it at its upper end for attaching the bit to a tubular string of drill pipe (not shown),

by means ofrwhich the bit is rotatable from the' surface of the bore hole, in a well-known manner. Depending downwardly from the main body is a pair of opposed legs 92, I2 rotatably carrying side or gauged tooth cutters l3, l3 whose purpose is to remove the outer portions of the formation material and maintain the hole to its required diameter. These cutters are each rotatably mounted on a disassemblable anti-friction bearing it to permit their replacement upon becoming worn.

The formation material within the annulus cut by the side rollers l3, I3 is removed by cross cutters of the drag or blade type. These cutters form part of an assembly 15, being preferably rigid or integral-with respect to each other, and consisting of outer drag cutters I6, I6 and inner drag cutters I1, I! disposed at an angle to the former; The upper portion Ila, of each inner cutter is preferably bevelled to clear the adjacent side cutter I3 and to lie closely adjacent the inner portions of the supporting bearing I l.

The drag cutter assembly I5 is securely attached to the main body H) of the bit by being welded to the legs [8, l8 depending from the body. These legs are positioned between the side cutter legs l2, l2 so that the central plane of the drag assembly 15 is approximately at right angles to the axes of rotation of the side cutters I 3, I3.

As described in my above referred to application, the outer drag cutters l6, l6 cut an annulus on the bottom of the hole with their outermost end portions preferably tracing a path having a radius at least equal to and preferably slightly greater than the radius of the inner circumference of the annul s of material removed by the side roller cutters l3, l3. Similarly. the central portion of the formation material is removed by the inner drag cutters l1, I! having a radius at least equal to and preferably slightly greater than the radius of the inner circle traced by the outer drag cutters l6, Hi. It is to be noted further that the lowermost radial toothed portions IQ of the side roller cutters lead or are positioned ahead of the bottoms Ilia, 16a of the outer drag cutters l8, IS in a downward vertical direction by a material extent, and that the lower contacting portions llb, 11b of the outer drag cutters l1, I! also lead the bottom contacting cutter portions in, "5a of the inner drag cutters. This arrangement is not only described in my application Serial No. 310,567, filed December 22, 1939, but is also claimed therein.

As disclosed in my prior application, only radial teeth l9 are supplied on the side roller cutters which are rotatable about downwardly and inwardly inclined axes. While very efiective in removing the outer annulus of formation material, the rotation of the cutters about such axes causes their inner faces 20 and also the inner faces of their teeth to merely rub against the downwardly and outwardly inclined shoulder 2| formed in the bottom of the hole as a result of the side roller teeth l9 leading the lower cutting edges lBa, lBa of the outer drag cutters. This frusto-conical shoulder is represented by the dotted line 2| in "Figure 3, which also indicates the position of the inner tooth face construction employed in the prior side roller cutters.

The lack of any adequate means on the side roller cutters for effectively removing this annular shoulder 2| has heretofore necessitated the lowering of the lower cutting edges l6a, I60. on the drag cutters, so that they might operate upon the material within the annulus formed by the side'roller cutters and prevent the production to any great extent of the shoulder 2i referred to. Although the teeth H! on the side roller cutters I3, l3 still led the lower drag cutting edges lfia, Ilia, the extent of their advance was limited, placing limitations upon the performance of the tool.

The present invention overcomes this difficulty by providing a set of inner, axially extending, reaming teeth 22 on each roller cutter l3. These axial teeth 22 merge smoothly into the radial teeth l9, there preferably being a bevelled, intermediate portion 23 connecting the two.

With the employment of the axial' teeth 22 extending inwardly of each roller cutter i3, the inclined shoulder that would be formed as a result of advancing the radial side cutter teeth 13 over the bottom edges llia, Ilia. of the drag cutters fails to impede progress of the bit, since the inner reaming teeth 22, 23 will effectively operate upon this inclined shoulder and produce-speedy removal of the formation. Since the penetration of the side roller teeth in the bottom of the hole is not impeded, it is no longer essential for the drag cutters l6, IE to be positioned low enough to prevent material production of the shoulder. For this reason, the lower cutting edges ltia, Ilia of the drag cutters can be elevated to a greater extent than heretofore, increasing the inherent tendency of the bit to make progress in a truly vertical direction. It is to be noted further that the employment of the inner set of reaming teeth 22, 23 also permits these drag cutters l6, ii to be decreased in width, since formation material formerly removed by their outermargins will now be removed by the inner axial teeth 22, 23.

The disposition of the inner set of drag cutters l1, II at an angle to the outer set IS, It enables a simple and sturdy bearing structure H to be employed in connection with each side roller cutter l3. Specifically, this bearing structure includes a threaded pin 24 preferably integral with a depending leg I2 and extending downwardly and inwardly therefrom, the axis of this threaded pin 24 being at right angles to the inclined inner surface 25 of the depending leg II. An interlorly threaded bearing sleeve 26 is screwed on the threaded pin 24 until its shoulder 21 abuts the inclined surface or face 25 of the leg l2. The exterior of the sleeve 26 is formed with a roller raceway 28 to receive the roller bearing members 29, and also with a ball raceway 30 to receive the ball bearing members 3i. The inner surfaces of each side roller cutter l3 are formed with roller and ball raceways 32, 33 opposed, respectively, to the roller and ball raceways 28, 30 in the sleeve 26, so that radial loadings imposed on the cutter i3 are transmitted between it and the sleeve 26 through both the roller bearings 29 and the ball bearings 31, while axial loadings are transmitted primarily through theball bearings 3|, which also serve to hold the cutter l3 and the various bearing elements 29, 3| in their proper positions on the raceways.

For the purpose of preventing disassembly of the side. roller bearing structure l4 while the drilling bit is in a well and to strengthen the entire bit, a threaded plug 34 is screwed into the sleeve 26 until its head 35 abuts the inner end 26a of the sleeve. Removal of this plug 34, and the consequent removal of the sleeve 26 from the threaded pin 24 is prevented by securing the outer ends of the inner drag cutters l1, H to the plug heads 35, as by means of welding material 36. This mode of attaching the plugs 34 to the inner cutters I1, I! not only offers assurance that each bearing structure [4 will be held in assembly, but also provides an additional support for the side cutters l3, I3,'eflectively tying the depending legs I2, l2 for the roller cutters together through the bearing supports l4, l4 and the inner drag cutters ll, l1.

One possible manner of assembling the side roller cutters l3, I3 on the bit consists in first. placing the roller bearings 29 in the sleeve raceway 28, and then sliding the cutter l3 over these rollers with its roller raceway 32 properly contacting them. The balls 3| are then inserted between their respective raceways 30, 33 from the threaded interior of the sleeve 26 through the hole 31 establishing communication between it and its ball raceway 30. After a sufficient number of balls has been inserted in place, a plug 38 is placed in the hole 31 from the interior of the sleeve 26 to prevent loss of the balls. This plug 38 has an outer curved surface to conform with the curvature of the raceway 30 and insure its continuity over its entire circumference. If desired, the inner end of the plug 38 may be threaded for cooperation with the threads on the plug 34. The sub-assembly of cutter l3, sleeve 26, rollers 29 and balls 3| is then mounted on the bit by threading the sleeve 26 on the pin 23 until its shoulder 21 abuts the inclined face 25 on the leg l2. threaded into the sleeve to its fullest extent. Following the placing of both roller cutters l3,

The plug 34 may then be I IS on the bit body III, the drag assembly I5 is' inserted between the other pair oi. depending legs threaded in the inner end of each sleeve, a second pair of legs depending from said body between sald first-mentioned pair, a drag assembly secured to said second pair of legs and having inner and outer cutters disposed at an angle to each other, said inner cutters being secured to said plugs to prevent their rotation.

2. A drill bit, including a main body having a pair of opposed depending legs, a pin extendthe inclined bearing pin 24. All worn parts can said pins.

ing inwardly and downwardly from each leg, a bearing sleeve secured on each pin and abutting its associated leg, a side roller cutter rotatably mounted on each sleeve, a second pair of legs depending from said body between said firstmentioned pair, a drag assembly secured to said second pair of legs and having inner and outer cutters disposed at an angle to each other, and means for securing said inner cutters to said bearing sleeves to prevent their removal from ARCHER W. KAMMERER- 

